In some traditional free space optical communication systems in which a relatively narrow optical beam serves as a communication link between two locations (e.g., an orbital space vehicle and a ground station), an optical beacon signal may be employed to facilitate accurate alignment of a receiving device with respect to a transmitting device for proper reception of an associated optical communication beam that carries communication data. Additionally, such as in cases in which the receiving device is located on an orbital or airborne vehicle, the optical beacon signal may also be employed to provide some suppression of vibrations imparted by the vehicle on the receiving device. In some examples, the optical beacon signal may be integrated in, or separate from, but in proximity with, the optical communication beam.
In some cases, the receiving system may control the orientation of one or more fine steering mirrors (or, alternately, fast steering mirrors (FSMs)) or other optical components designed to receive the optical beacon signal using a beam location detection device. In addition, the beam location detection device may employ a quadrant photodetector that provides some indication of the location of the optical beacon signal within the field of view (FOV) of the quadrant photodetector.
Quadrant photodetectors that may be deemed suitable for optical beacon signals in such cases may exhibit a range of FOVs. However, while quadrant photodetectors with relatively wide FOVs may initially be favored over relatively narrow FOV quadrant photodetectors to facilitate detection of the optical beacon signal over a greater FOV, wide FOV quadrant photodetectors typically exhibit greater atmospheric scintillation noise than narrow FOV quadrant photodetectors, possibly rendering their outputs less accurate.